The present invention refers to a method of repairing pallets whose elements are attached to each other by means of connector members, particularly of EURO wood pallets having five top deck board members, three stringer board members and three bottom deck board members, whereby the bottom deck board members are attached to the stringer board members by means of connecting block members and whereby the afore mentioned pallet members are attached to each other by means of connector members, particularly nails. Moreover, the invention refers to an assembly for performing the above mentioned method, with a disassembly station for cutting through the connector members fixing the pallet elements to each other, with an assembly station for attaching the new pallet elements as well as with an apparatus for applying new connector members while the pallet is in the assembly station.
The German Patent Publication DE-A-43 08 580 discloses a method and an apparatus for repairing damaged pallets. The damaged pallet is positioned and fixed on a machine table with its top side facing downwards. Thereafter, the damaged connecting blocks and board members are cut out with a separating device that is movable in three coordinate axes. The separating device comprises a machine head provided with a vertically running drive shaft. At the end of the drive shaft, a rotating circular saw blade is attached. The diameter of the circular saw blade is chosen such that it is smaller than the distance between the rows of connecting block members extending in longitudinal direction. Thus, the circular saw blade can be moved into the space between two adjacent rows of connecting block members extending in longitudinal direction, with the result that the damaged elements of the pallet can be selectively sawn off. Upon separating the damaged elements, the connector means, —nails —, are cut through. After the damaged elements having been removed, the pallet is transferred to a supply and assembly station where the elements to be replaced are fed to the corresponding location and positioned. The real attachment of the new parts is performed by means of two nailing devices, simultaneously driving in nails from the top and from the bottom.
The German Patent Publication DE-A-198 22 229 also discloses a method and an apparatus for repairing damaged wooden pallets. According to this publication, in a first step, the damaged board members and/or skids are separated from the pallet to be repaired. In a second step, the new parts are aligned to the pallet and thereafter nailed thereto. In a further step, the pallets are pressed, such that nails not fully driven in and board members not fully seated are brought into proper position. The apparatus for performing these method steps comprises a feed conveyor for feeding in the pallets, a de-stacker for singularizing the pallets, a disassembly station for selectively separating damaged parts, an assembly station for replacing the damaged parts, a centering and nailing station for attaching the replaced parts as well as a pressing station for pressing in protruding nails and not fully seated board members.
It is the object of the present invention to improve a method and an assembly for repairing damaged pallets in such a way that the pallets can be repaired quickly, simply and reliably.
To meet these and other objects, the invention provides a method of repairing pallets whose elements are attached to each other by means of connector members, particularly of EURO wood pallets having five top deck board members, three stringer board members and three bottom deck board members. In these pallets, the bottom deck board members are attached to the stringer board members by means of connecting block members and the afore mentioned pallet members are attached to each other by means of connector members, particularly nails. According to the invention, in a first method step, the connector members of the pallet member to be replaced or of the pallet members to be replaced are cut through and the pallet member to be replaced or the pallet members to be replaced is/are removed. In a subsequent method step, both the new pallet members and the partially disassembled pallet are transferred to an assembly station, and in a further subsequent method step, the new pallet members are attached in the assembly station to the pallet by applying new connector members, whereby all new connector members are applied either from the top side of the pallet or from the bottom side of the pallet.
To further meet these and other objects, the invention also provides an assembly for performing the afore mentioned method, with a disassembly station for cutting through the connector members fixing the pallet elements to each other, with an assembly station for attaching the new pallet elements as well as with an apparatus for applying new connector members while the pallet is in the assembly station. According to the invention, a testing station is provided in front of the assembly station, said testing station comprising means for recognizing missing pallet elements and/or means for recognizing the position of connector elements present in one or several top deck board members of a partially disassembled pallet
One basic feature of the invention may be seen in the fact that, in a first method step, the connector members of the pallet members to be replaced are cut through, that, in a subsequent method step, both the new pallet members and the partially disassembled pallet are transferred to an assembly station, and that, in a further subsequent method step, the new pallet members are attached in the assembly station to the pallet by applying new connector members, whereby all new connector members are applied from the top side of the pallet. In order to ensure that the connector members can be applied exclusively from the top side of the pallet, the pallet is preferably repaired by replacing pallet modules, whereby a damaged bottom deck board member is removed always in the form of a skid, i.e. together with the three assigned connecting block members. Thus, a new skid can be attached to the pallet easily from the top side thereof. Preferably, prior to attaching a new skid, the position of the connector elements still present in the top deck board member above the new skid to be attached is scanned and stored, such that the new connector members can be applied in a position offset to the already present connector members. This is an important prerequisite for a reliable and durable attachment of the new skid, because, in this way, the danger is eliminated that the new connector members are deflected or even burst off during their application by the already present connector members. In order to recognize whether or not any elements and modules, respectively, of the pallet are missing and, if positive, which elements and modules, respectively, preferably an automatic testing station is provided. This testing station preferably is also provided with sensors for scanning the position of connector elements still present in the top deck board members. By the aforementioned measures, simultaneously the prerequisite is created for an essentially fully automated repair of the pallets.